15,350 research outputs found
Drastic disorded-induced reduction of signal amplification in scale-free networks
Understanding information transmission across a network is a fundamental task
for controlling and manipulating both biological and man-made information
processing systems. Here, we show how topological resonant-like amplification
effects in scale-free networks of signaling devices are drastically reduced
when phase disorder in the external signals is considered. This is demonstrated
theoretically by means of a star-like network of overdamped bistable systems,
and confirmed numerically by simulations of scale-free networks of such
systems. The taming effect of the phase disorder is found to be sensitive to
the amplification's strength, while the topology-induced amplification
mechanism is robust against this kind of quenched disorder in the sense that it
does not significantly change the values of the coupling strength where
amplification is maximum in its absence.Comment: 5 pages, 4 (double) figure
Flux switching alternators for small wind generation
This paper considers the application of flux
switching alternators for small wind generation. First, after a
brief presentation of the small wind energy systems, a description
and the fundamentals of flux switching machines is given, then
the state of art of flux switching generators is presented. Finally
a critical assessment is shown, considering the main advantages
and drawbacks of this type of machines as alternator for use in
small wind generation systems.Peer ReviewedPostprint (published version
Which quantum states are dual to classical spacetimes?
It is commonly accepted that states in a conformal field theory correspond to
classical spacetimes with Anti-de-Sitter asymptotics. In this work we give a
prescription for the CFT states with a dual classical spacetime and, using
basic holographic rules, show that they are holographically connected to
coherent states in the large-N limit, or by considering linearized
perturbations. We also point out implications in the spacetime emergence
mechanism, for instance, the (entangled) state dual to the black hole should be
properly described as a quantum superposition of products of these states. This
also complements the quantum interpretation of the Hawking-Page transition.Comment: 14 pages, 8 figure
Impact of Gamma Radiation on Dynamic RDSON Characteristics in AlGaN/GaN Power HEMTs
GaN high-electron-mobility transistors (HEMTs) are promising next-generation devices in the power electronics field which can coexist with silicon semiconductors, mainly in some radiation-intensive environments, such as power space converters, where high frequencies and voltages are also needed. Its wide band gap (WBG), large breakdown electric field, and thermal stability improve actual silicon performances. However, at the moment, GaN HEMT technology suffers from some reliability issues, one of the more relevant of which is the dynamic on-state resistance (RON_dyn) regarding power switching converter applications. In this study, we focused on the drain-to-source on-resistance (RDSON) characteristics under 60Co gamma radiation of two different commercial power GaN HEMT structures. Different bias conditions were applied to both structures during irradiation and some static measurements, such as threshold voltage and leakage currents, were performed. Additionally, dynamic resistance was measured to obtain practical information about device trapping under radiation during switching mode, and how trapping in the device is affected by gamma radiation. The experimental results showed a high dependence on the HEMT structure and the bias condition applied during irradiation. Specifically, a free current collapse structure showed great stability until 3.7 Mrad(Si), unlike the other structure tested, which showed high degradation of the parameters measured. The changes were demonstrated to be due to trapping effects generated or enhanced by gamma radiation. These new results obtained about RON_dyn will help elucidate trap behaviors in switching transistors
Variational Principles for multisymplectic second-order classical field theories
We state a unified geometrical version of the variational principles for
second-order classical field theories. The standard Lagrangian and Hamiltonian
variational principles and the corresponding field equations are recovered from
this unified framework.Comment: 6 pp. Minor corrections. Clarifications and comments have been added.
Two new sections ("Introduction" and "The higher-order case") have been
added. Bibliography enlarge
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